Sealed subs generally provide tighter (more highly damped) bass than ported models. You can check "group delay" specs at HTShack.com (if they're available for the models you're considering) and you'll see one measure of this characteristic. The trade-off is less true deep bass output per cubic foot of enclosure volume.
Most people prefer sealed subs for music, because you don't need a ton of clean output in the 20hz region for music (tho you might for cinema) and tighter bass is often (tho not always) a better match for high-end main speakers.
Most people prefer sealed subs for music, because you don't need a ton of clean output in the 20hz region for music (tho you might for cinema) and tighter bass is often (tho not always) a better match for high-end main speakers.